Gastric mucosal smooth muscles may explain oscillations in glandular pressure: role of vasoactive intestinal peptide.
OBJECTIVE
Oscillating (3-7 cycles/min) high pressures in gastric glands during acid secretion suggest the existence of rhythmically contracting mucosal muscles. The aim of this study was to study vasoactive intestinal peptide (VIP), an inhibitory neurotransmitter in the gastrointestinal tract, in relation to mucosal muscles, glandular pressure, and blood flow.


METHODS
Rat, dog, and human mucosae were examined immunocytochemically for smooth muscle actin and VIP. Glandular pressure was measured using microelectrodes, red blood cell velocity (V[RBC]) was measured using a cross-correlation technique, and blood flow was measured using laser Doppler flowmetry in exposed gastric mucosa of thiobutabarbital sodium-anesthetized rats.


RESULTS
Actin immunostaining showed muscle strands arising from muscularis mucosae, extending toward the gastric pits. VIP-immunoreactive nerve fibers were found in close relation to these muscles. VIP, administered intra-arterially close to the stomach (2 microg/kg bolus, followed by 10 microg x kg[-1] x h[-1]), significantly decreased glandular pressure from 18.2 +/- 1.6 to 8.9 +/- 1.6 mm Hg and almost eliminated the pressure oscillations. VIP infusion also abolished the oscillations in V(RBC) and significantly increased blood flow by approximately 35%.


CONCLUSIONS
Contracting mucosal muscles may be responsible for oscillations in glandular pressure and possibly also in V(RBC). VIP probably relaxes these muscles.
Synnerstad
I
I
Department of Physiology and Medical Biophysics, Biomedical Center, Uppsala University, Sweden.
Ekblad
E
E
Sundler
F
F
Holm
L
L
D000818:Animals; D004285:Dogs; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000033:anatomy & histology* / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D006801:Humans; D006874:Hydrostatic Pressure; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000033:anatomy & histology* / Q000294:innervation / Q000502:physiology; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000502:physiology; D010507:Periodicity; D051381:Rats; D011917:Rats, Inbred Lew; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology / Q000502:physiology*
D014660:Vasoactive Intestinal Peptide